a small function to compile cpp/java code on eshell

compile-current-cpp-java-file.el

(defun compile-current-cpp-file ()
  "Compile and run current file on eshell"
  (interactive)
  (let ((filename (buffer-file-name)))
    (with-selected-window (get-buffer-window "*eshell*")
      (recenter)
      (insert "g++ -std=c++11 " filename " -o a.out && ./a.out")
      (eshell-send-input)
      (erase-buffer))
    (message "File '%s' is compiled and ran" filename)))

(defun compile-current-java-file ()
  "Compile and run current file on eshell"
  (interactive)
  (let ((filename (buffer-file-name))
        (filename-wo-extension (file-name-nondirectory (file-name-sans-extension buffer-file-name))))
    (with-selected-window (get-buffer-window "*eshell*")
      (recenter)
      (insert "javac " filename " && java " filename-wo-extension)
      (eshell-send-input)
      (erase-buffer))
    (message "File '%s' is compiled and ran" filename)))

(add-hook 'c++-mode-hook
          '(lambda ()
             (local-set-key (kbd "C-c C-c") 'compile-current-cpp-file)))

(add-hook 'java-mode-hook
          '(lambda ()
             (local-set-key (kbd "C-c C-c") 'compile-current-java-file)))

I personally use a 3 window setup.

+-------------------------+-----------------------------+
|                         |                             |
|                         |                             |
|                         |                             |
|                         |      input file             |
|                         |                             |
|                         |                             |
|                         |                             |
|                         |                             |
|                         |                             |
|       CODE              +-----------------------------+
|                         |                             |
| freopen("input file",   |                             |
|   "r", stdin);          |                             |
|                         |                             |
|                         |         eshel               |
|                         |                             |
|                         |                             |
|                         |                             |
|                         |                             |
|                         |                             |
+-------------------------+-----------------------------+

now as soon as I am done with coding, I can just press C-c C-c and I can view the result in the eshell prompt